/**
* Money Flow Index (MFI) Indicator
* Volume-weighted momentum oscillator
*/
export interface MFIData {
mfi: number | null
signal: 'overbought' | 'oversold' | 'neutral' | null
trend: 'bullish' | 'bearish' | 'neutral' | null
}
export function calculateMFI(
highs: number[],
lows: number[],
closes: number[],
volumes: number[],
period: number = 14
): MFIData {
// Minimum 5 data points required
if (highs.length < 5 || lows.length < 5 || closes.length < 5 || volumes.length < 5) {
return {
mfi: null,
signal: null,
trend: null,
}
}
// Use adaptive period
const effectivePeriod = Math.min(period, highs.length - 1)
// Calculate Typical Price and Raw Money Flow
const typicalPrices: number[] = []
const rawMoneyFlows: number[] = []
for (let i = 0; i < closes.length; i++) {
const typicalPrice = (highs[i] + lows[i] + closes[i]) / 3
typicalPrices.push(typicalPrice)
rawMoneyFlows.push(typicalPrice * volumes[i])
}
// Calculate Positive and Negative Money Flow
const positiveFlows: number[] = []
const negativeFlows: number[] = []
for (let i = 1; i < typicalPrices.length; i++) {
const currentTP = typicalPrices[i]
const previousTP = typicalPrices[i - 1]
const rawMF = rawMoneyFlows[i]
if (currentTP > previousTP) {
positiveFlows.push(rawMF)
negativeFlows.push(0)
} else if (currentTP < previousTP) {
positiveFlows.push(0)
negativeFlows.push(rawMF)
} else {
positiveFlows.push(0)
negativeFlows.push(0)
}
}
// Calculate Money Flow Ratio for the specified period using effective period
const usePeriod = Math.min(effectivePeriod, positiveFlows.length)
const startIdx = Math.max(0, positiveFlows.length - usePeriod)
const periodPositiveFlows = positiveFlows.slice(startIdx)
const periodNegativeFlows = negativeFlows.slice(startIdx)
const positiveMF = periodPositiveFlows.reduce((sum, flow) => sum + flow, 0)
const negativeMF = periodNegativeFlows.reduce((sum, flow) => sum + flow, 0)
if (negativeMF === 0) {
return {
mfi: 100,
signal: 'overbought',
trend: 'bullish',
}
}
const moneyFlowRatio = positiveMF / negativeMF
const mfi = 100 - (100 / (1 + moneyFlowRatio))
// Determine signal
let signal: 'overbought' | 'oversold' | 'neutral' | null = null
if (mfi >= 80) signal = 'overbought'
else if (mfi <= 20) signal = 'oversold'
else signal = 'neutral'
// Determine trend (comparing with previous MFI if available)
let trend: 'bullish' | 'bearish' | 'neutral' | null = null
if (positiveFlows.length > period) {
const prevStartIdx = startIdx - 1
if (prevStartIdx >= 0) {
const prevPositiveFlows = positiveFlows.slice(prevStartIdx, prevStartIdx + period)
const prevNegativeFlows = negativeFlows.slice(prevStartIdx, prevStartIdx + period)
const prevPositiveMF = prevPositiveFlows.reduce((sum, flow) => sum + flow, 0)
const prevNegativeMF = prevNegativeFlows.reduce((sum, flow) => sum + flow, 0)
if (prevNegativeMF > 0) {
const prevMoneyFlowRatio = prevPositiveMF / prevNegativeMF
const prevMFI = 100 - (100 / (1 + prevMoneyFlowRatio))
if (mfi > prevMFI) trend = 'bullish'
else if (mfi < prevMFI) trend = 'bearish'
else trend = 'neutral'
}
}
}
return {
mfi,
signal,
trend,
}
}
